Overload release for power presses



Oct. 18, 1949. u. MULLER OVERLOAD RELEASE FOR POWER PRESSES 2Sheets-Sheet 1 Filed Oct. 22, 1947 HVVENTDR; JuLEs MULLEH BY' flow $doauA TTYS- 0a. 18, 1949. J. MULLER 2,485,009

OVERLOAD RELEASE FOR POWER PRESSES Filed 001;. 22, 1947 2 Sheets-Sheet 2IN VEN TOR. JuLEs MULLER ATTYSI Patented Oct. 18, 1949 l'fules lmiller,

bhtwere Chicago, Ill., "a'ssig'nor to E. W. Bliss Company, Detroit,Mich.,

a corporation of elnplicationflotoberZZ, 1947-, Serial No. 781,398

, "'1 i'llaim. 1 r 1 This invention relates reshape-forming, bl'a'ilkingor drawing presses, and has particular reference to pressure relievingmeans Iforthe 'forming or drawing .parts when a predetermined overloadpressure has been developed thereby. I

"In the use oi presses o'f'this eharacterthe workshaping orldlanliingpartswhich aremechanieally adjustalil'e as to travel oi thework coacting parts, are subjected times to varyin overloads occasioned,for "instance, variations in the hardness "of theWdlknialtrlial "or inthe thickness thereof, which ma result in severe damage to the pressparts and dies and cause spoilage of the work. These -severe overloadsfrequently cause breakage or bending of theipress parts as 'well asstalling, resulting in costly repairs and thelo'ss or production. 7 I

The ob'j'ect of the present invention is to prevent or reduce 'sue'hfailures and the resultant cost of repairs and loss of production to aminimum by interposing 'anovel, "simple :"and efficient safety unit inthe pressure producing linkage or "connections of the "This "unit is "ofa nature to "be interposed "in ,praetically any pressure applyinglinkage of the press and does not become-operative to relieve*anoverloaa condition until a redetermined pressure is applied to thelink.

As an illustration, the "four-point 'blan-k "holder of 'ajmecharfioal"press rated at 506 tons will apply, through proper linkage, 1 25 tonsat each corner connection of the Blank holder. The amount "of travel ofthe lzilar'rk hblder is "adjustable "according to the *thiekness o'f thematerial processed. When the thickness or the material excee as that for*wnieh the travel "to produce the desired ressure is adjusted, anoverload will be "imposed "on 'th'e 'pre'ss. isrmnany, a press withrated plunger "capacity ot say ron tons single point will be subjectedto fa large overload on the pressure protruding linkage when by accidenttw'o '-or more thiclnnesses of material, o'r material of greaterthikness orihardness, or or higher physical properties thanthoseforwhiehthepress is set, ar'e introduced into the were "performing*point o'f' the press.

"The invention is hilly ide's'efiibeil hr *the following s ecification,two embodiments thereof illustrated "in the accompanying drawings, in

in se arated form of "the pressure "rings 'u'sedin "connec'tionwfththemvefition, w'lthparts 2 broken away, and Fig. 4 is a side view of a dif-'ferent form of linkage embodying the invention, with parts in central"longitudinal section.

Referring to the drawings, Fig. 1 illustrates a conventional form ofpower press for sheet metal stamping work, or the like, "and indlu'des ab'lank holder i operating in frame guides '2. The blank holder has therequired rediprcrcatory movement imparted thereto from an overheadoperating means by a plurality "of iinks 3, usually four in number, oneat each corner of the blank holder, "as well understood in the art, "andthe yieldin'g means embodying the invention is interposed, in thepresent instance, between each link and the respective corner "of theblank holder.

This means, in the illustrated embodiment thereof shown in Fig. 2,comprises-'9, plunger' h'ead 5 with which the respective link 3 haspivoted or universal thrust connection and which has a stem ii projecteddownward theretrom through an opening 1 in a registering portion 8 ofthe blank holder. This'stemis threaded and carries a top "thrust nut "9above the portion 8' and a hollow thrust =nut P0 below said portion. Thestem 6 is freely enc'ir'cled'between said thrus't parts with 'athrustsleeve H having an annular radial flange or enlargement 4-2 at its upperend which receives the thrust-of the part 9. The lowerend of this sleeveprojects below the blank holder part 3 and receives a nut I -3"intermediate the-said part and the nut -'l-ll, -so that, in the presentin-- -'stance, the blank holder part =8 is supported by the stem 6 andnut l'n through the medium of the nut 13.

The blank holder opening I has an enlargement 1 above its lower endportion, which latter -gu'idingly fits the sleeve l l, and its upper endis iurther enlarged, as at 7 to receive and guide the axis-1 movementsiof the sleeve -enlargemen't [2, with the enlargement n'orrrrall-yspaced from the bottom (if the portion ii.

'The sleeve H, at its upper end adjacent to the enlargement I2, isprovided with a downwardly facing conical annular seat It *c'oncentricto the sleeve axis, and in the bottom of the opening enlargement W is anupwardly "facing conical "collar 15. Surrounding "the sleeve Hintermediate the'c'o'ni-cal seats 14 and I5 arean inner set "of spacedrings 16 and "an outer set of spaced rings I1, which latter alternatewith the rings of the inner set with the end or top and hottom'rings ofthe outer set in *endWise thrust'en- 'gagement with therespeotive'conioal'seats Hand 15. The inner rings l6 'closelyhug-the's'leeve H "while the outer rings H arepre'ferably spacedslightly from the sleeve, and the meeting corner portions of the ringsof both sets are beveled or tapered so that the rings of one set willhave tapered or wedge-like coaction with those of the other set. It isthus apparent that when longitudinal pressure is applied to the set ofrings having engagement with the conical seats l4 and I5, there will bea tendency for the rings of such set to radially expand due to thecoaction of the tapered surfaces. When such expansion takes place underpredetermined overload pressures, the sleeve M will be permitted to moveinward a slight distance relative to the part 8 into which it projects,whereby to compensate for the overload pressure.

When the parts of the yielding pressure means have been assembled asabove described, the outer ring elements as a set are axially compressedand at the same time are radially expanded to suit the pressure to beapplied to the blank holder through such connection during normaloperation of the press. Should an overload beyond such normal operatingpressure be applied, from any cause. through the connection to the blankholder, as by increased thickness of material acted on or increasedhardness thereof, the rings of the outer set will be relativelycompressed axially of the sleeve H and, due to the action of the taperedsurfaces l4 and on the end rings of the outer set and tapered coactionof the outer rings with the tapered surfaces of the inner rings, therings I? will be radially expanded, thus allowing the safety connectionto yield sufiiciently to prevent any undue strain to be imposed on thepress parts. To render the rings l6 and H yielding, they are made ofsuitable spring steel.

The safety connection is given the desired tension to withstand yieldingunder normal loads by an adjustment of the nuts 9 and [0 on the stem 6and an adjustment of the nut l3 on the sleeve H, as is apparent, and theconnection then will not yield under normal operating conditions, butonly when a predetermined overload pressure is applied. The elasticityin the rings is sufiicient to cause them to return to their normalcontracted positions for which adjusted when relieved of the Overloadcondition and to return the parts of the connection to their normalpositions for which adjusted. It will be understood that while theyielding connection has been shown as including two inner rings l6 andthree outer rings H, the rings may be increased or diminished in numberto suit the particular application. The space l in which the rings aredisposed is filled with oil.

In the modification of the yielding connection shown in Fig. 4, 25designates a part of the linkage or other pressure applying means of thepress, 2! a part to which pressure is applied and which may be attachedto or comprise, for instance, a part of the press blank holder with theconnection therebetween comprising the invention.

The part 2! has a stepped socket 22 therein in line with the thrustaction of the part and forming near its bottom the annular shoulder 23and near its top the annular shoulder 24. The yieldingly mounted thrustsleeve 25 is inserted into the socket 22 in radially spaced relation tothe socket wall and terminates at its inner end short of the shoulder23. The outer end of the sleeve 25 has a radial flange or enlargement 26fitting into the outer enlarged end of the socket and held inpredetermined spaced relation to the shoulder 24 by screws 21 looselyinserted through apertures therein and threaded into said shoulder. Thescrew heads serve as stops to limit the outward movements of the sleeverelative to the part 2| on which mounted. In the angle between thesleeve and its flange is provided an annular tapered surface 28concentric to the sleeve axis, and mounted on the sleeve between thistaper and the socket shoulder 23 are, in the, presentinstance, two innerrings 25 with tapered outer edges and an end ring seating on theshoulder 22 and having a single tapered surface 3| facing the sleevetaper 28. A plurality of rings 32 forming an outer set alternate withand have tapered inner edges bearing againstthe registering taperededges of the inner rings 29 and the respective tapered surfaces 28 and3I,'as shown. The rings 32 resist an inward movement of the sleeve 25relative to the socket shoulder 23 and ring 30 seating thereon, and uponthe application of a predetermined overload pressure to the sleeve 25,the rings 32 are relatively contracted in an axial direction and therebycaused to ride out on the coacting tapered surfaces and to radially exand the same as in the first-described form.

The inner end of the sleeve 25 is threaded internally to a nipple 33that projects through the ring 30 and shoulders thereunder. It isapparent that either an inward adjustment of the sleeve 25 by atightening of the screws 21 or an adjustment of the nipple 33 relativeto the sleeve will adjust the tension of the yielding connection. Thesleeve 25, nipple 33 and interposed rings 29, 30 and 32 form an assemblywhich may be inserted in or removed as a unit from engagement with themember 2 I.

The member 20 has a bar or rod 35 threaded therein in the line of thrustfor adjustment relative thereto, and this is shown as having anenlargement 36 shouldering against the outer end of the sleeve 25 or itsflange 26. A stem 31 projects from this enlargement freely into thesleeve 25 and has its free end reduced and freely projected through thenipple 33 and engaged at its end by a nut 38 that bears against theouter end of the nipple so that the yielding assembly unit is carried bythe member 35 in clamped relation between the enlargement 36 and saidnut.

In either form of the invention the yielding connecting means may bereversed with respect to the pressure applying and pressure receivingelements, as no difference in operation or result would thereby beefiected. The only differencewould be that the sleeve II in one case and25 in the other case, in one position of the yielding unit, would serveas the pressure applying element and in the reverse position thereofwould serve as the pressurereceiving element.

While in both forms the yielding characteristic under abnormal loadconditions has been described as taking place in the outer set of ringsby expansion thereof, it is apparent that under high pressures there maybe and probably is some compression of the innerrings and other partswith which the outer rings coact. It is, of course, apparent that theinner rings may be made of very hard material which is non-compressibleunder pressure conditions encountered in stamping or drawing presses, sothat all of the yieldability of theconnection takes place in the outerset of rings. Ordinarily, however, in practice there will probably besome give or yieldability in all coacting tapered surfaces with that oftheouter rings the greater.

I wish it understood that my invention is not limited, to any specificonstruction, arrangement or form of the parts, as it is capable ofnumerous modifications without departing from the spirit of the claim.

Having thus described my invention, what I claim as new, and desire tosecure by United v States Letters Patent, is:

In a pressure applying linkage for a power inner set and having wedgecoaction whereby relative axial movements thereof cause expanding actionof the outer rings, one of said outer rings having a tapered seat on theflange portion of said sleeve, means anchored to the free end of 6 saidstem and having tapered thrust coaction with an end ring of said outerset, said means "having thrust coaction with said thrust-receiving partwhereby a yielding of said rings under thrust action permits relativeinward movements of said sleeve and thrust-receiving part, saidthrust-receiving part cooperating with the flange of said sleeve to forma housing for said rings.

JULES MULLER.

REFERENCES CITED ,The following references are of record in the file ofthis patent:

I UNITED STATES PATENTS Number Name Date ,989,433 Symington Jan. 29,1937 2,359,915 Hussman Oct. 10, 1944 2,413,740 Wik-ander Jan. 7, 1947

